THE driver of a car which plunged down a ravine killing a young mid Wales volunteer probably fell asleep at the wheel.

An Welshpool inquest heard Rebecca Louise Owen died of head injuries after the black sedan-style car pitched off a hairpin bend in Mexico.

It fell around 25 metres down the cliff face crashing though trees.

The 22-year-old Ancient History and Archaeology graduate, from Llanfechain, Powys, was on a round-the-world trip after leaving university.

She was working at a turtle conservation centre in Jalisco state with UK firm Teaching and Projects Abroad.

Fellow volunteer Chloe Taylor, who was in her 20s and from Tunbridge Wells, Kent, was also killed in the February smash.

Rebecca and 11 other volunteers borrowed the car to visit a network of caves to collect data on bats.

Sometime after 10pm Carlos Napoleon Ibarra Cerdena, who worked for the gap-year firm - started to drive back to the group's base.

The 29-year-old Peruvian biologist later told police he was dazzled by on-coming headlights and swerved to avoid a vehicle on the Carretera Federal 80 near La Huerta.

After the crash he called out his companions' names and all answered except Miss Owen and Miss Taylor.

The two women were dead when medical crews arrived at the scene.

Mr Ibarra was arrested on the grounds he was driving too fast and had overloaded the car which seated nine people.

Powys coroner Geraint Williams told the hearing he was later charged with reckless homicide.

Working from reports provided by the Mexican authorities Mr Williams said he could find no evidence to prove the driver was speeding.

"It seems to me that this was a driver who was as tired as his colleagues.

"They had all been awake and working for the bulk of the day and all of the other witnesses ( passengers) described being tired and asleep or half asleep.

"There is no evidence of any action by the driver to avoid the collision. He would have been very sleepy and perhaps wouldn't have noticed the road turning sharply to the left until it was far too late."

He recorded a verdict of accidental death.

Rebecca's grandad Chris Tyler said: "She was living her dream. We were getting messages from her saying how every day was terrific. And that is of some comfort to us."